In many medical procedures, it is necessary to introduce a fluid into the body. This fluid may be a relatively passive fluid, e.g. saline, or it may be a relatively active agent, e.g. an anticoagulant drug, an antibiotic drug, etc. Such fluids are typically introduced into the body by means of a catheter. Catheters generally comprise a tube-like body having a distal end for positioning inside the body at the point where the fluid is to be administered, and a proximal end for positioning outside the body so as to be readily accessible for the introduction of fluid into the catheter. In some circumstances the proximal end of the catheter may be placed subcutaneously near the outside of the body, where it may be accessed by a subcutaneous needle arrangement when fluid is to be delivered through the catheter.
In the case of active fluids such as anticoagulant drugs, the distal end of the catheter is traditionally positioned within a major artery or vein so that the fluid is introduced systemically into the entire body. However, in many cases it may be preferable to provide the active fluid to only a specific region of the body and not to the body as a whole. Thus, for example, in the case of anticoagulant drugs, catheters have been used to introduce anticoagulants at specific surgical sites so that the anticoagulant can be selectively applied to only the desired surgical site. In the case of anticancer drugs, catheters have been used to introduce powerful chemotherapy agents into the vessels or biliary tree of the liver for selective application to the cancerous area of the liver. In such cases, the catheter is implanted in the body so that its distal end is located in a specific region of the body where the active fluid is to be introduced, with the proximal end of the catheter being located in an easily-accessed position outside, or just inside, the body.
Unfortunately, since catheters have been traditionally formed out of a permanent, non-bioabsorbable material, emplacement of a catheter with its distal end deep within the body has traditionally required a second, subsequent surgical procedure to remove the catheter from its place in the body once it is no longer needed. This requirement of a second, subsequent surgical procedure has obvious disadvantages. This is particularly true if the catheter has been placed in an artery, since the subsequent removal of the catheter from the artery may cause further bleeding. In addition, the need for a second, subsequent surgical procedure to remove the catheter may make emplacement of the catheter in a deep, non-readily accessible portion of the body unacceptable in certain circumstances.